1. Field of the Invention
The present invention relates to exercise machines, in particular a leg press typically used to strengthen the legs of a user.
2. Description of Related Art
Exercise machines have become a popular device for strengthening a user's muscles. One such type of machine is a leg press. A typical leg press will have a push plate that can move relative to a frame. The user will sit in a seat and push the plate with his legs, so that the plate moves from a rest position to an extended position. The push plate is coupled to some type of force resistance means, which provides a reactive force to the pushing motion of the user. The force resistance means is typically a weight stack that is lifted when the plate is moved toward the extended position. The weight stack is usually connected to the plate by a cable/pulley assembly. Movement of the push plate will pull a cable and lift the weight stack. The pulleys guide the cable and insure cable tension between the plate and weights.
When operating a leg press, the user typically begins the exercise routine with his legs bent, wherein movement of the push plate results in the straightening of the legs. Generally speaking, as the legs straighten, the leg muscles attain a leveraged advantage such that the strength of the user increases as the legs are extended to a straightened position. Consequently, when the user of a leg press machine pushes the push plate forward, the legs are able to apply a greater force as the legs move toward an extended position. To counteract this increase in leg strength it is desirable to provide a resistive force that matches the strength curve of the user. Present leg press machines with cable/pulley assemblies have provided either a linear resistance curve, or a resistance curve that both increases and decreases as the push plate is pushed forward. It would therefore be desirable to provide a cable/pulley leg press machine that provides a nonlinear increasing resistance curve that approximates the strength curve of a user.
Cable/pulley leg press machines typically incorporate a pair of linkage arms that are coupled to the push place. When the user pushes the plate forward, the plate is deflected through an angle as the linkage arms move through an arc. The plate deflection can induce an incorrect bio-mechanical movement of the user's feet, thereby causing undesirable stress in the ankle joints. It would therefore be desirable to have a leg press machine that provides bio-mechanically correct movement of the push plate.
Exercise machines are typically constructed from rugged metal components to support the user and weight stack of the system. When the user allows the push plate of a leg press to move from the extended position to the rest position, the linkage arms of the cable/pulley assembly tend to abruptly strike the frame. The sudden impact of the metal members is somewhat noisy and introduces a shock to the system. It would therefore be desirable to have a leg press machine that provides a nonlinear increasing resistance curve, bio-mechanically correct movement, and a cushioned stop that absorbs shock and reduces the noise of the machine.